U.S. patent application number 11/970538 was filed with the patent office on 2009-07-09 for stator bar components with high thermal conductivity.
This patent application is currently assigned to GENERAL ELECTRIC COMPANY. Invention is credited to Elena Rozier, Jeffrey David Sheaffer, David John Wardell.
Application Number | 20090174278 11/970538 |
Document ID | / |
Family ID | 40343746 |
Filed Date | 2009-07-09 |
United States Patent
Application |
20090174278 |
Kind Code |
A1 |
Sheaffer; Jeffrey David ; et
al. |
July 9, 2009 |
Stator Bar Components with High Thermal Conductivity
Abstract
A stator bar. The stator bar may include a number of conductors
and an insulation layer positioned about the conductors. The
insulation layer includes a ceramic component.
Inventors: |
Sheaffer; Jeffrey David;
(Glenville, NY) ; Rozier; Elena; (Schenectady,
NY) ; Wardell; David John; (Ballston Spa,
NY) |
Correspondence
Address: |
SUTHERLAND ASBILL & BRENNAN LLP
999 PEACHTREE STREET, N.E.
ATLANTA
GA
30309
US
|
Assignee: |
GENERAL ELECTRIC COMPANY
Schenectady
NY
|
Family ID: |
40343746 |
Appl. No.: |
11/970538 |
Filed: |
January 8, 2008 |
Current U.S.
Class: |
310/201 ;
174/113R; 174/124G |
Current CPC
Class: |
H02K 3/30 20130101 |
Class at
Publication: |
310/201 ;
174/113.R; 174/124.G |
International
Class: |
H02K 3/30 20060101
H02K003/30; H02K 3/04 20060101 H02K003/04; H02K 3/34 20060101
H02K003/34 |
Claims
1. A stator bar, comprising: a plurality of conductors; and a
fabric insulation layer positioned about the plurality of
conductors; wherein the insulation layer comprises a ceramic
component.
2. The stator bar of claim 1, wherein the ceramic component
comprises ceramic fibers or whiskers.
3. The stator bar of claim 1, wherein the fabric insulation layer
comprises a thermal conductivity of more than about 0.99 W/mK.
4. The stator bar of claim 1, wherein the ceramic component
comprises boron nitride (BN), aluminum nitride (AlN), silicon
nitride (Si3N4), aluminum oxide (Al2O3), magnesium oxide (MgO),
zinc oxide (ZnO), strontium titanate (SrTiO3), titanium dioxide
(TiO2), silica (SiO2), or diamond (C).
5. The stator bar of claim 1, wherein the fabric insulation layer
comprises a combination of glass and the ceramic component.
6. The stator bar of claim 1, wherein the fabric insulation layer
comprises only the ceramic component.
7. The stator bar of claim 1, wherein the fabric insulation layer
comprises a plurality of glass or polymeric fibers in a first
direction and wherein the ceramic component comprises a plurality
of ceramic fibers in a second direction.
8. The stator bar of claim 1, wherein the plurality of conductors
comprises two or more tiers of conductors and wherein the fabric
insulation layer comprises a vertical separator between each of the
tiers.
9. The stator bar of claim 1, wherein the fabric insulation layer
comprises a layer of ground insulation surrounding a plurality of
tiers.
10. The stator bar of claim 9, wherein the layer of ground
insulation comprises a tape.
11. The stator bar of claim 9, wherein the layer of fabric
insulation comprises a mica/binder layer and wherein the ceramic
component comprises a backer to the mica/binder layer.
12. A stator bar, comprising: two or more conductor tiers; and a
fabric vertical separator between each of the tiers; wherein the
vertical separator comprises a ceramic component.
13. The stator bar of claim 12, wherein the ceramic component
comprises ceramic fibers or whiskers.
14. The stator bar of claim 12, wherein the fabric vertical
separator comprises a thermal conductivity of more than about 0.99
W/mK.
15. The stator bar of claim 12, wherein the ceramic component
comprises boron nitride (BN), aluminum nitride (AlN), silicon
nitride (Si3N4), aluminum oxide (Al2O3), magnesium oxide (MgO),
zinc oxide (ZnO), strontium titanate (SrTiO3), titanium dioxide
(TiO2), silica (SiO2), or diamond (C).
16. A stator bar, comprising: two or more conductor tiers; and a
layer of fabric ground insulation surrounding the tiers; wherein
the layer of fabric ground insulation comprises a ceramic
component.
17. The stator bar of claim 16, wherein the layer of fabric ground
insulation comprises ceramic fibers or whiskers.
18. The stator bar of claim 16, wherein the layer of fabric ground
insulation comprises a thermal conductivity of more than about 0.99
W/mK.
19. The stator bar of claim 16, wherein the ceramic component
comprises boron nitride (BN), aluminum nitride (AlN), silicon
nitride (Si3N4), aluminum oxide (Al2O3), magnesium oxide (MgO),
zinc oxide (ZnO), strontium titanate (SrTiO3), titanium dioxide
(TiO2), silica (SiO2), or diamond (C).
20. The stator bar of claim 16, wherein the layer of fabric ground
insulation comprises a mica/binder layer and wherein the ceramic
component comprises a backer or backers to the mica/binder layer.
Description
TECHNICAL FIELD
[0001] The present application relates generally to insulating
systems for electrical machines and more particularly relates to
improving the thermal conductivity of insulation used with stator
bar components through the addition of high thermal conductivity
fibers or whiskers such as ceramics, including non-traditional
non-metallic materials.
BACKGROUND OF THE INVENTION
[0002] Insulation materials for electrical machines such as
generators, motors, and transformers generally include a glass
cloth and/or a combination of a glass cloth, a resin binder, a mica
tape, and similar materials. Such insulating materials generally
need to have the mechanical and the physical properties that can
withstand the various electrical rigors of the electrical machines
while providing adequate insulation. In addition, the insulation
materials should withstand extreme operating temperature variations
and provide a long design life.
[0003] In recent years, the thermal conductivity of general
insulation has improved from about 0.3 W/mK to about 0.5 W/mK
(Watts per meter per degrees Kelvin) via the addition of high
thermal conductivity fillers. Specifically with respect to stator
bars, however, E-glass (electrical fiberglass) generally is used to
insulate the conductors, as a vertical separator, and as a backer
in insulating tapes. Such E-Glass may have a thermal conductivity
of about 0.99 W/mK. Similarly, a Dacron glass (Daglass) also may be
used. Daglass may have a thermal conductivity of about 0.4
W/mK.
[0004] By reducing the thermal resistance of the stator bar
components, improved heat transfer may be obtained between the
stator bar conductors and the stator core. Specifically, the
current density of the copper conductor may be increased by
effectively cooling the conductors. There is thus a desire for even
further thermal conductivity improvements so as to produce more
power from a smaller unit at a more economical cost or at a higher
efficiency from an existing unit.
SUMMARY OF THE INVENTION
[0005] The present application thus describes a stator bar or
similar type of armature coil. The stator bar may include a number
of conductors and an insulation layer positioned about the
conductors. The insulation layer may include a ceramic
component.
[0006] The present application also describes a stator bar with two
or more conductor tiers and a vertical separator between each of
the tiers. The vertical separator may include a ceramic
component.
[0007] The present application further describes a stator bar with
two or more conductor tiers and a layer of ground insulation
surrounding the tiers. The layer of ground insulation may include a
ceramic component.
[0008] These and other features of the present application will
become apparent to one of ordinary skill in the art upon the review
of the following detailed description when taken in conjunction
with the several drawings and the following claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a perspective view of a stator bar as is described
herein.
[0010] FIG. 2 is a side cross-sectional view of a stator bar as is
described herein.
[0011] FIG. 3 is a side cross-sectional view of a stator bar as is
described herein.
[0012] FIG. 4 is a side cross-sectional view of a stator bar as is
described herein.
[0013] FIG. 5 is a side cross-sectional view of an insulating tape
as is described herein.
DETAILED DESCRIPTION
[0014] Referring now to the drawings, in which like numerals refer
to like elements throughout the several views, FIG. 1 shows a
stator bar 100 as is described herein. As described above, the
stator bar 100 may be used with electrical machines as is known in
the art. An electrical machine generally has multiple stator bars
100. The multiple stator bars 100 may be identical and may be
disposed upon or about each other.
[0015] Generally described, each stator bar 100 may include a
number of conductors 120. The conductors 120 may be made out of
copper, copper alloys, aluminum, or similar materials. A layer of
conductor insulation 130 may separate individual conductors 120. In
this example, the conductor insulation 130 may include a typical
E-Glass, Daglass, or a similar type of glass material. The E-Glass
may be a low alkali borosilicate fiberglass with good
electro-mechanical properties and with good chemical resistance.
E-Glass, or electrical grade glass, has excellent fiber forming
capabilities and is used as the reinforcing phase in fiberglass.
The E-Glass may have a thermal conductivity of about 0.99 W/mK. The
Daglass may be a yarn with a mixture of polyester and glass fibers.
The Daglass may have a thermal conductivity of about 0.4 W/mK. A
glass cloth made from the E-Glass, the Daglass, or from similar
types of materials may have any desired woven densities, weights,
thicknesses, strengths, and other properties.
[0016] In the embodiment as shown, the stator bar 100 includes two
tiers 140 of the conductors 120. Any number of tiers 140 may be
used. The tiers 140 may be separated by a vertical separator 150.
Typical vertical separators 150 may include paper, felt, or a glass
fabric that is treated with a partially cured resin that, when
cured, flows and bonds the tiers 140 together. The separators 150
also provide added electrical insulation between tiers 140.
[0017] The tiers 140 also may be surrounded by a layer of ground
insulation 155. As described above, the ground insulation 155
commonly may be constructed of mica paper, a glass cloth or
unidirectional glass fibers, and a resin binder. The ground
insulation 155 generally is in the form of a resin rich tape.
[0018] FIG. 2 shows a stator bar 100 with an improved conductor
insulator 160. The conductor insulator 160 includes the E-Glass or
the Daglass of the conductor insulation 130 with the addition of
ceramic component of fibers or whiskers. For example, aluminum
oxide fibers or whiskers may have a thermal conductivity of about
20 W/mK. The improved conductor insulator 160 thus may incorporate
such ceramic fibers or whiskers into a weave of the glass cloth or
incorporate it into glass yarns so as to improve the thermal
conductivity of the material to much higher than that of pure
glass. The resultant fabric also could have the ceramic fibers or
whiskers in one direction with the Daglass or other material in the
other. Alternatively, the improved conductor insulator 160 may be a
pure aluminum oxide cloth or a cloth of a similar ceramic
material.
[0019] In this example, the ceramic fibers, whiskers, or other
forms may include boron nitride (BN), aluminum nitride (AlN),
silicon nitride (Si3N4), aluminum oxide (Al2O3), magnesium oxide
(MgO), zinc oxide (ZnO), strontium titanate (SrTiO3), titanium
dioxide (TiO2), silica (SiO2), diamond (C), and similar types of
materials.
[0020] By wrapping the improved conductor insulator 160 around the
conductors 120, the thermal conductivity may increase. For example,
certain conductors 120 may be closer to the source of the magnetic
field and hence may be subject to higher magnetic fields. Such
higher magnetic fields may induce higher currents so as to set up a
temperature differential between the closer and the farther
conductors 120 within the stator bar 100. Use of the improved
conductor insulator 160 described herein may allow for improved
heat flow and a lower temperature difference between the respective
conductors 120. Likewise, certain stator bars 100 may use hollow
conductors to serve as passages for fluid flow therethrough so as
to remove heat from the stator bar 100 as a whole. In such designs,
the use of the improved conductor insulator 160 should allow more
efficient cooling and a higher ratio of solid to hollow conductors
120. As a result, the amount of copper in the conductors 120 may
increase in a stator bar 100 of the same size.
[0021] FIG. 3 shows a further embodiment of a stator bar 200. The
stator bar 200 may be similar to that described above but with an
improved vertical separator 210. As above, the improved vertical
separator 210 may be a mixture of paper, felt, or the glass fabric
along with the ceramic fibers or whiskers so as to provide improved
heat transfer between the tiers 140. As described above, the fibers
or whiskers may include boron nitride (BN), aluminum nitride (AlN),
silicon nitride (Si3N4), aluminum oxide (Al2O3), magnesium oxide
(MgO), zinc oxide (ZnO), strontium titanate (SrTiO3), titanium
dioxide (TiO2), silica (SiO2), diamond (C), and similar types of
materials.
[0022] FIGS. 4 and 5 show a further embodiment of a stator bar 250.
As described above, the ground insulation 155 of the stator bar 100
may be commonly constructed of mica paper, glass, and a resin
binder. This insulation is generally in the form of a resin rich
tape. In this case, the stator bar 250 has an improved ground
insulation 260. The improved ground insulation 260 may include the
ground insulation 155 described above with the addition of the
ceramic fibers or whiskers. Specifically, the improved ground
insulation 260 has a mica/binder layer 270 and a ceramic backer 280
on one or both sides of the mica/binder layer 270. In this case,
the conventional E-glass or Daglass backer may be replaced or mixed
with the ceramic material so as to provide higher thermal
conductivity.
[0023] It should be apparent that the foregoing relates only to the
preferred embodiments of the present application and that numerous
changes and modifications may be made herein by one of ordinary
skill in the art without departing from the general spirit and
scope of the invention as defined by the following claims and
equivalents thereof.
* * * * *